| 401 | Talos Third Coast LLC | | Oil & Gas Operator | Dec 2024 |
| 402 | Tellus Energy, LLC | | Oil & Gas Operator | Dec 2024 |
| 403 | Tellus Operating Group, LLC | | Oil & Gas Operator | Dec 2024 |
| 404 | Tenneco Oil Company | Oklahoma City, OK 73125 | Oil & Gas Operator | Dec 2024 |
| 405 | Terra Resources, Inc. | Casper, WY 82601 | Oil & Gas Operator | Jun 1990 |
| 406 | Terrier Oil Company | | Oil & Gas Operator | Feb 2015 |
| 407 | Tesoro E&P Company, L.P. | San Antonio, TX 78216 | Oil & Gas Operator | Jan 2000 |
| 408 | Tesoro Petroleum Corporation | | Oil & Gas Operator | May 1982 |
| 409 | Tex-Con-Brehm-Basin Expl. | | Oil & Gas Operator | May 1990 |
| 410 | Tex/Con Oil & Gas Company | Houston, TX 77074 | Oil & Gas Operator | Feb 2001 |
| 411 | Texaco E & P Inc | Houston, TX 77099 | Oil & Gas Operator | Mar 2025 |
| 412 | Texaco Inc | Kingfisher, OK 73750 | Oil & Gas Operator | Dec 2017 |
| 413 | Texaco Producing Inc. | Rock Springs, WY 82901 | Oil & Gas Operator | Dec 2000 |
| 414 | Texas Meridian Res. Expl., Inc. | Houston, TX 77079 | Oil & Gas Operator | Jun 1998 |
| 415 | Texas Petroleum Investment Company | Houston, TX 77057 | Oil & Gas Operator | Mar 2025 |
| 416 | The Dow Chemical Company | | Oil & Gas Operator | Dec 1997 |
| 417 | The Meridian Res. & Exp. LLC | | Oil & Gas Operator | Sep 2010 |
| 418 | The Meridian Resource & Exp Co | | Oil & Gas Operator | Dec 2000 |
| 419 | The WM G Helis Company, L.L.C. | | Oil & Gas Operator | Nov 2003 |
| 420 | Time Energy, L.L.C. | | Oil & Gas Operator | Nov 2020 |
| 421 | Tipco | Shreveport, LA 71104-3047 | Oil & Gas Operator | May 1988 |
| 422 | Toce Oil Company | | Oil & Gas Operator | Dec 2014 |
| 423 | Torch Operating Company | Houston, TX 77010 | Oil & Gas Operator | Mar 2015 |
| 424 | Torch Opr Co-Stone Petr Corp | | Oil & Gas Operator | Jul 1997 |
| 425 | Transcontinental Gas P/L Corp. | | Oil & Gas Operator | Dec 2009 |
| 426 | Tricentrol Resources Inc | Englewood, CO 80111 | Oil & Gas Operator | Jun 1984 |
| 427 | Trigon Exploration, Inc. | | Oil & Gas Operator | Jan 1999 |
| 428 | TXP Operating Company | | Oil & Gas Operator | Jul 1992 |
| 429 | Ultramar Oil & Gas LTD | Houston, TX 77060 | Oil & Gas Operator | Jul 1995 |
| 430 | Union Exploration Partners, LTD. | | Oil & Gas Operator | Aug 1990 |
| 431 | Union Oil Co Of California | Midland, TX 79706 | Oil & Gas Operator | Jan 2022 |
| 432 | Union Pacific Resources Co. | Fort Worth, TX 76101 | Oil & Gas Operator | Sep 2002 |
| 433 | Union Texas Petroleum Corp. | Houston, TX 77252-2120 | Oil & Gas Operator | Dec 2014 |
| 434 | Unit Petroleum Company | Tulsa, OK 74170 | Oil & Gas Operator | Mar 2025 |
| 435 | United Gas Pipe Line Co. | | Oil Operator | Aug 1993 |
| 436 | United Operators, Inc. | | Oil Operator | Sep 1999 |
| 437 | Unocal Exploration Corporation | | Oil & Gas Operator | May 1992 |
| 438 | Us Oil & Gas Inc | Marietta, OH 45750 | Oil & Gas Operator | Jan 2025 |
| 439 | Vanguard Environmental, LLC | | Oil Operator | Nov 2024 |
| 440 | Venvirotek Of Louisiana, Inc. | | Oil Operator | Apr 2002 |
| 441 | Vernon E. Faulconer, Inc. | Tyler, TX 75711 | Oil & Gas Operator | Dec 2024 |
| 442 | Vintage Petroleum, Inc. | Houston, TX 77046 | Oil & Gas Operator | Dec 2024 |
| 443 | Virgin Offshore U.S.A., Inc. | | Oil & Gas Operator | Oct 2012 |
| 444 | W & T Offshore, Inc. | Houston, TX 77057 | Oil & Gas Operator | Mar 2025 |
| 445 | W. W. F. Oil Corporation | | Oil & Gas Operator | Dec 1999 |
| 446 | Wagner Oil Company | Fort Worth, TX 76102 | Oil & Gas Operator | Mar 2025 |
| 447 | Wainoco Oil & Gas Company | Houston, TX 77024 | Oil & Gas Operator | Dec 2005 |
| 448 | Wallace Operating Company | | Oil & Gas Operator | Sep 1986 |
| 449 | Walter Oil & Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 450 | Wayman W. Buchanan | | Oil & Gas Operator | Feb 1986 |
| 451 | Weaver Exploration Company | | Oil & Gas Operator | Jun 1991 |
| 452 | Weeks Exploration Company | Houston, TX 77063 | Oil & Gas Operator | Aug 1995 |
| 453 | Wes-Tex Drilling Company | Abilene, TX 79604 | Oil & Gas Operator | Jan 2000 |
| 454 | White Oak Operating Company LLC | Houston, TX 77077 | Oil & Gas Operator | Mar 2025 |
| 455 | Whiting Oil And Gas Corporation | Houston, TX 77002 | Oil & Gas Operator | Mar 2025 |
| 456 | Whiting Petroleum Corporation | Denver, CO 80290 | Oil & Gas Operator | Aug 2024 |
| 457 | Whitney Oil & Gas, LLC | | Oil & Gas Operator | Jan 2025 |
| 458 | WHK, Inc. | | Oil & Gas Operator | Oct 1993 |
| 459 | Williams Exploration Company | | Oil & Gas Operator | Dec 1986 |
| 460 | Windfohr Oil Company | | Oil & Gas Operator | May 1980 |
| 461 | Wintershall Corporation | | Oil & Gas Operator | Oct 1989 |
| 462 | Wintershall Oil & Gas Corp | Houston, TX 77027 | Oil & Gas Operator | Jul 1989 |
| 463 | Woods & Deas-Dobie | | Oil & Gas Operator | Aug 1983 |
| 464 | WRT Energy Corporation | Oklahoma City, OK 73118 | Oil & Gas Operator | May 1998 |
| 465 | Xplor Energy Operating Co. | Houston, TX 77079 | Oil & Gas Operator | Jan 2012 |
| 466 | XTO Energy Inc. | Spring, TX 77389 | Oil & Gas Operator | Mar 2025 |
| 467 | Zadeck Energy Group Inc | | Oil & Gas Operator | Dec 2011 |
| 468 | Zeit Exploration Co., Inc. | | Oil & Gas Operator | May 1994 |
| 469 | Zenergy Inc | Tulsa, OK 74136 | Oil & Gas Operator | Jan 2025 |
| 470 | Zinke & Trumbo, Inc. | Tulsa, OK 74136 | Oil & Gas Operator | Mar 2007 |